Existing techniques for biometrics-based authentication systems include methods that employ recognition of various biometric tokens including, for example, fingerprint, face, hand, and iris recognition. Various biometric choices have strengths and weaknesses depending on their systems' applications and requirements. The present discussion focuses on hand-based biometric analysis. The geometry of the hand contains relatively invariant features of an individual. In existing systems, hand-based authentication is sometimes employed in small-scale person authentication applications due to the fact that geometric features of the hand (e.g., finger length/width, area/size of the palm) are not as distinctive as fingerprint or iris features.
However, existing techniques and systems rely on outmoded or inconvenient processes in order to increase identification accuracy. Among these include strict requirements about hand orientation. Existing systems go as far as to require the use physical pegs or guides to direct hand orientation during image capture in order to allow assumptions to be made during analysis which simplify computational requirements. Such requirements are undesirable from a user's perspective, however, because they make use of such a system cumbersome and potentially uncomfortable. Additionally, adding physical restrictions to a system increases the likelihood that the system will require special, costly equipment.
Another strict requirement in existing techniques is the method by which they perform recognition of an image of a hand. Many existing systems and techniques focus on extraction of several landmark points on the surface or silhouette of the hand in order to identify the shape. This point extraction is not performed easily and is frequently prone to localization errors. Such errors can, by altering the very shape and borders of the segments created, substantially increase the difficulty of performing verification or identification. Additionally, existing systems and techniques require the recognition of lines or prints on the hand or fingers in order to perform analysis. Such identification is more prone to error, both from acquisition mistakes and from inconsistencies in hand appearance from day to day.
What is needed is a system that can perform biometric analysis for identification and/or verification which does not require restrictions on hand placement to the extensive degree used in existing systems. Additionally, what is needed are techniques for performing such biometric analysis that are robust with regard to changes in placement and changes in points and lines on the hand itself.